Interface I2S with HDMI Audio input on W4S and others

[fmak]

I am keen on trying to interface my W4S DAC2DSDSE I2S input from generic XMOS usb to I2S boards

(eg Wave IO and others). The Twisted Pear Transporter and K&K Audio Send boards are possibilities but

there is an interface mismatch (RJ45) from the Transporter and apparent reversal in signal polarities with the

K&K Send board and Juli@ board.

 

Has anyone on the forum successfuly done it and how? Perhaps Chris can also chime in.

 

I have asked EJ a couple of times about his suggestion of an interface board but so far there is no news.

[pooger]

I'd ask this on the DIY forums, especially the twisted Pear one, and also at the TP support site. Both Russ and Brian are very good about answering questions, and someone else may know about reworking the interface. I have no idea if it's as simple as a plug converter, or if there are impedance, etc. issues. I've read that people have had good experiences with the channel island USB to I2S with your DAC.

[4est]

FWIW, when done well, i2s is worth the effort over spdif. The teleporter(transporter) has solder pads too IIRC. If that is what your are talking about.

 

Twisted Pear - diyAudio

[vortecjr]

I am keen on trying to interface my W4S DAC2DSDSE I2S input from generic XMOS usb to I2S boards

(eg Wave IO and others). The Twisted Pear Transporter and K&K Audio Send boards are possibilities but

there is an interface mismatch (RJ45) from the Transporter and apparent reversal in signal polarities with the

K&K Send board and Juli@ board.

 

Has anyone on the forum successfuly done it and how? Perhaps Chris can also chime in.

 

I have asked EJ a couple of times about his suggestion of an interface board but so far there is no news.

 

The send board will work fine and there is no signal reversal. You can refer to my i2s database.

 

http://www.i2s.sonore.us

 

Jesus R

[barrows]

fmak: I have implemented the Twisted Pear Audio teleporter as an I2S receiver, wired to an HDMI jack, and I see no reason why it would not work as a transmitter as well. The Teleporter typically does not use the G connection, but I find that performance is much better with ground connected, so I connect the Teleporter G to the HDMI ground as per the PS Audio I2S over HDMI specification.

[fmak]

The send board will work fine and there is no signal reversal. You can refer to my i2s database.

 

http://www.i2s.sonore.us

 

Jesus R

 

I am not a member of Google and don't want to sign up.

[fmak]

fmak: I have implemented the Twisted Pear Audio teleporter as an I2S receiver, wired to an HDMI jack, and I see no reason why it would not work as a transmitter as well. The Teleporter typically does not use the G connection, but I find that performance is much better with ground connected, so I connect the Teleporter G to the HDMI ground as per the PS Audio I2S over HDMI specification.

 

Would very much appreciate details - a schematic? I am new to hdmi audio connectors and connections

[gstew]

Would very much appreciate details - a schematic? I am new to hdmi audio connectors and connections

 

Hey Fred!

 

Fidelix in Japan did a couple of adapter boards for an audio over HDMI via LVDS that were compatible with the PS Audio configuration and they showed the schematics in post #202 of the Bunpei & Chiaki's MicroSD Memory Card Transport thread over on DIYAudio... here: MicroSD Memory Card Transport Project - Page 5 - diyAudio .

 

Grab that and if you don't have them already, get the K&K interface manual from K&K and the Teleporter manual or schematic (not sure they have a manual for it) from Twisted Pear and I suspect that'll be enough to figure it out.

 

Also, since the LVDS signals are differential with no reference to ground, I believe you can just swap the wires for a signal pair if the polarity is not wired correctly between the sender and receiver. I'm sure someone will correct me if I'm wrong about this, tho!

 

Greg in Mississippi

 

P.S. Barrows, thanks for the tip on the ground connection with the Teleporters. BTW, did PS Audio publish their specification anywhere or can one get it by asking?

[barrows]

Hey Fred!

 

Fidelix in Japan did a couple of adapter boards for an audio over HDMI via LVDS that were compatible with the PS Audio configuration and they showed the schematics in post #202 of the Bunpei & Chiaki's MicroSD Memory Card Transport thread over on DIYAudio... here: MicroSD Memory Card Transport Project - Page 5 - diyAudio .

 

Grab that and if you don't have them already, get the K&K interface manual from K&K and the Teleporter manual or schematic (not sure they have a manual for it) from Twisted Pear and I suspect that'll be enough to figure it out.

 

Also, since the LVDS signals are differential with no reference to ground, I believe you can just swap the wires for a signal pair if the polarity is not wired correctly between the sender and receiver. I'm sure someone will correct me if I'm wrong about this, tho!

 

Greg in Mississippi

 

P.S. Barrows, thanks for the tip on the ground connection with the Teleporters. BTW, did PS Audio publish their specification anywhere or can one get it by asking?

 

PS Audio has published the pin out for their interface, as they want it to be open source and for other folks to adapt it as a new "standard" for LVDS I2S signals over HDMI. I believe it is published at diyaudio.com, somewhere... I suspect that a request for it from PS Audio customer service would also suffice. Also, Wyred 4 Sound uses the same interface on their DACs, so they should be able to provide info as well.

[4est]

With all of this talk about Twisted Pear and i2s, it seems prudent for me to mention this. You can get i2s directly out of a RaspPi now, and there will be a TP cape for the Beaglebone Black soon. The Pi sounds pretty good, and I hear the BBB is better. With an audiophile clock cape, it could be a sweet little gizmo. There may be a reason why Russ of TP saw no real benefit using one of his USB designs. I'd consider this route if you are looking to run i2s.

 

Building an open embedded audio applicance. - diyAudio

[fmak]

With all of this talk about Twisted Pear and i2s, it seems prudent for me to mention this. You can get i2s directly out of a RaspPi now, and there will be a TP cape for the Beaglebone Black soon. The Pi sounds pretty good, and I hear the BBB is better. With an audiophile clock cape, it could be a sweet little gizmo. There may be a reason why Russ of TP saw no real benefit using one of his USB designs. I'd consider this route if you are looking to run i2s.

 

Building an open embedded audio applicance. - diyAudio

 

I am talking about feeding HDMI based dac; you are talking about another OS. Fine, but the 2 are not related.

[4est]

I am sorry that you feel that was off topic, but others may be interested. You mentioned i2s via a WaveIO or similar. I am getting as good or better i2s out of this RPi as I got out of the WaveIO I have using a TP Shunt regulator. If one is willing to DIY a Teleporter for LVDS as discussed, they might consider provisions for something akin to these simple computers. I tried Volumio RPi i2s for kicks this weekend, and was quite surprised what $50 and 1 hour got me.

[gstew]

I am sorry that you feel that was off topic, but others may be interested. You mentioned i2s via a WaveIO or similar. I am getting as good or better i2s out of this RPi as I got out of the WaveIO I have using a TP Shunt regulator. If one is willing to DIY a Teleporter for LVDS as discussed, they might consider provisions for something akin to these simple computers. I tried Volumio RPi i2s for kicks this weekend, and was quite surprised what $50 and 1 hour got me.

 

I'd agree I2S out of an RPi or BBB is off-topic (and now so am I, sorry!). And using a pair of TP Teleporter (which are LVDS devices) to get I2S out of one of those to your DAC is exactly what they were designed for. AND, AFAIK, after a quick comparison of the Teleporter, the Fidelix circuit, and the K&K I2S over HDMI boards along with some of the relevant datasheets, they should all be interoperable as long you observed correct matching of input to output wiring pairs and polarities.

 

As I see it, they are best used when:

 

1. You are using a DAC that performs async reclocking (like the TP Buffalo or K&K RAKK DAC) or ARE using a device like Ian's FIFO Reclocker, as the LVDS interface will add some jitter.

 

2. You can't just put the DAC board within an inch or two of the transport's I2S output, as longer non-LVDS I2S connections add more jitter than using LVDS.

 

3. You want to setup several transports with a compatible I2S output and switch between them into your DAC with just a cable swap.

 

4. You have a commercial transport which already has a compatible I2S output and you want to use that instead of SPDIF (or USB if it is a computer transport).

 

5. You have a commercial DAC which already has a compatible I2S input and you want to use it with an I2S output transport, such as what Fred intends to do.

 

I like the idea of the RPi and BBB as computer transports and using an LVDS I2S connection IF you can't just locate your DAC right at the board's I2S outputs. And once Fred gets his Wave IO (or other generic USB->I2S adapter) to W4S DAC2DSDSE I2S connection worked out, he can share that with us here and others using the W4S DAC2DSDSE via I2S input can benefit from his experience... and even use that as a way to connect either an RPi or BBB as the transport.

 

Greg in Mississippi